During the operation of small- and large-scale combustion devices, such as boilers, furnaces, and other such devices that burn fossil fuels (or pulp and paper recovery mill, and oil refineries), slag and ash encrustations develop on interior surfaces of the boiler. The presence of these deposits degrades the thermal efficiency of the boiler. Therefore, it is periodically necessary to remove such encrustations. Various systems are currently used to remove these encrustations.
One such type of system is referred to as a “sootblower.” Sootblowers are used to project a stream of cleaning fluid (e.g., air, steam, water, CO2, environmental control chemical, etc.) through one or more nozzles against interior surfaces of the boiler. In the case of a retracting type sootblower, a lance tube is periodically advanced into and withdrawn from the boiler. As the lance tube is moved into and out of the boiler, it may also rotate or oscillate in order to direct one or more jets of cleaning fluid at desired surfaces within the boiler. In the case of stationary sootblowers, the lance tube is maintained within the boiler and is periodically activated to discharge cleaning fluid. Sootblower lance tubes penetrate the boiler through openings in the boiler wall, referred to as wall ports. The wall ports may include a mounting assembly, such as a wall box, in order to mount the sootblower to the boiler wall and seal the port.
Another such type of system includes a device commonly referred to as a “water cannon.” Water cannons involve the use of a monitor or nozzle positioned within a wall port in order to eject a stream of fluid, such as water, against the interior surfaces of the boiler. The water cannon nozzle typically includes a pivot joint to permit adjustment of the direction of the stream of fluid. Similar to the sootblower, the water cannon nozzle is positioned within the wall port via a mounting assembly, such as a wall box. Unlike the sootblower, however, the water cannon nozzle preferably includes a pivotable ball or cardon joint coupled with the wall box in order to adjust the direction of the stream of fluid flowing into the boiler interior volume. Due to the presence of the pivotable joint, the wall port for a water cannon assembly is typically larger than the wall port for a sootblower. As a result, water cannons generally require greater installation costs than sootblowers.
Conventional sootblowers deliver the cleaning fluid into the boiler at a high pressure to facilitate the removal of the encrustations. Supplying steam or water to the boiler consumes energy and lowers the overall efficiency of the boiler system. Therefore, cleaning should be done only when needed. Conventional sootblowers have nozzles mounted in a fixed position to the lance tube and are inserted into a boiler longitudinally along a single axis and are rotated about that axis, and therefore have limited cleaning ranges. Consequently, such sootblowers are not capable of spraying the cleaning fluid against all of the nearby surfaces within the boiler requiring cleaning.
Furthermore, sootblowers cleaning with steam or water carry the risk of causing steam tube erosion. Rapid deterioration of the boiler steam tubes can occur as a result of thermal shock from the cleaning process. The potential for damage to the boiler surfaces is greater if the cleaning fluid is sprayed against a bare boiler tube after it has been cleaned, such that the cleaning fluid contacts the surface directly rather than contacting an encrustation on the surface. If a particular sootblower has an insufficient range of cleaning, an array of adjacent sootblowers may be provided at additional cost. In such cases, the jet stream from two or more adjacent sootblowers may overlap one another to the extent that certain areas of the heated surfaces become excessively cleaned and therefore deteriorate. Conventional sootblowers, due to limitations in their articulation, do not provide a constant rate of cleaning medium progression along the surfaces to be cleaned. This leads to insufficient cleaning of some areas, and over cleaning of others.
In addition to guarding against the potential deterioration of the boiler surfaces being cleaned, it is also desirable to guard against component damage of the sootblower coupled to the wall box of the boiler. In particular, due to the hostile conditions of the interior of an operating boiler, components entering the interior of the boiler (e.g., nozzles, lance tubes, etc.) may experience heat-related stresses and corrosion. As a result, it has been observed that the hostile environment in which sootblowers are employed pose significant maintenance challenges.
In view of the above, there is a need in the art to provide an improved sootblower for cleaning heated surfaces of small- and large-scare combustion devices.